Tracing: Remove UI at Settings > Monitor > Tracing

What does this MR do and why?

This MR aims to solve the issue #351388 (closed)

Remove deprecated tracing UI from Settings > Monitor > Tracing tab

Screenshots or screen recordings

Before	After

app/views/projects/settings/operations/_tracing.html.haml

-- setting = tracing_setting
-
-%section.settings.border-0.no-animate
-  .settings-header{ :class => 'border-top' }
-    %h4.settings-title.js-settings-toggle.js-settings-toggle-trigger-only
-      = _('Tracing')
-    %button.btn.btn-default.gl-button.js-settings-toggle{ type: 'button' }
-      = _('Expand')
-    %p
-      = _('Embed an image of your existing Jaeger server in GitLab.')
-      = link_to _('Learn more.'), help_page_path('operations/tracing'), target: '_blank', rel: 'noopener noreferrer'
-  .settings-content
-    = form_for @project, url: project_settings_operations_path(@project), method: :patch do |f|
-      = form_errors(@project)
-      .form-group
-        = f.fields_for :tracing_setting_attributes, setting do |form|
-          = form.label :external_url, _('Jaeger URL'), class: 'label-bold'
-          = form.url_field :external_url, class: 'form-control gl-form-input', placeholder: 'https://jaeger.example.com'
-          %p.form-text.text-muted
-            - jaeger_help_url = 'https://www.jaegertracing.io/docs/getting-started/'
-            - link_start_tag = '<a href="%{url}" target="_blank" rel="noopener noreferrer">'.html_safe % { url: jaeger_help_url }
-            - link_end_tag = "#{sprite_icon('external-link', css_class: 'gl-ml-2 gl-vertical-align-middle')}</a>".html_safe
-            = _('Learn more about %{link_start_tag}Jaeger configuration%{link_end_tag}.').html_safe % { link_start_tag: link_start_tag, link_end_tag: link_end_tag }
-      = f.submit _('Save changes'), class: 'gl-button btn btn-confirm'